This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Surface enhanced Raman spectroscopy (SERS) nanoparticles have distinct spectral bands that can be exploited for biomedical diagnostics. In particular, SERS particles have emerged as promising beacons for flow cytometry. Because SERS particles have distinct Raman spectra with high signal to noise, they have the potential to be used for multiplexing assays that require not only great dynamic range but also narrow spectral bandwidths to discriminate between events . We are working towards the characterization of SERS particles using flow cytometry systems developed at LANL, including the spectral, phase-sensitive and high-resolution instruments.